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Light LED on PPDB — Parallax Forums

Light LED on PPDB

NWCCTVNWCCTV Posts: 3,629
edited 2015-02-20 16:35 in General Discussion
I just received my PPDB and I want to get working with it. I am a bit skeptical as there are no instructions for it. I can't even get one of the LED's to light up! Is there suppose to be another power source to the LED's? I am running a simple blink program and it does not work. I have a 470 Ohm resistor between pin 1 and Vss. I am powering the board with a 9V wall wart. What am I missing?

Comments

  • ElectrodudeElectrodude Posts: 1,658
    edited 2015-02-19 20:09
    I'm assuming you mean the built-in bank of 16 LEDs. Is your 470 Ohm resistor sinking power from the Prop's IO line straight to ground, or is it connected between LED 1 and ground?

    None of the Prop's IO lines (other than 28-31) are connected to anything unless you connect them yourself. The LEDs already have resistors suitable for 3.3V (and probably 5V too, but don't quote me on that). Plug a wire in from Propeller pin 1 to one of the holes in the black header near the row of 16 LEDs, and then try blinking it.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2015-02-19 20:16
    Thank you. I was looking at the Schematic and thought I needed a 470 Ohm in the mix. I did what you suggested and it worked great. Thanks again.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2015-02-19 20:36
    Andy,

    In case you're not aware, tonyp12 sells a board with some shift registers to allow one to control the 16-segment displays with a single I/O pin.

    http://forums.parallax.com/showthread.php/134106-Updated-17seg-LED-driver-for-PPDB-now-available

    It's possible to control the displays without shift registers but it uses up a lot of the Propeller's I/O pins.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2015-02-19 21:17
    Cool. Thanks Duane.
  • homosapienhomosapien Posts: 147
    edited 2015-02-20 04:29
    " I am a bit skeptical as there are no instructions for it."

    Description and schematic here, under 'Downloads and Documentation', easy-peasy. -> http://www.parallax.com/product/32111
  • NWCCTVNWCCTV Posts: 3,629
    edited 2015-02-20 11:15
    So do all the components on the PPDB have built in resistors? From the way I am reading it they do but I want to verify before moving on.
  • PublisonPublison Posts: 12,366
    edited 2015-02-20 12:09
    NWCCTV wrote: »
    So do all the components on the PPDB have built in resistors? From the way I am reading it they do but I want to verify before moving on.

    Have you looked at the schematic?

    http://www.parallax.com/sites/default/files/downloads/32111-PPDB-RevA-Schematic.pdf

    It's kinda all there in black and white.
  • ercoerco Posts: 20,256
    edited 2015-02-20 14:47
    Publison wrote: »
    Have you looked at the schematic? It's kinda all there in black and white.

    Yeah fine, but what are all those lines and squiggles and dots and zigzaggles?
  • NWCCTVNWCCTV Posts: 3,629
    edited 2015-02-20 14:57
    Thanks guys and thanks erco. One of those brain fart days. It is raining!!!!
  • PublisonPublison Posts: 12,366
    edited 2015-02-20 15:43
    Sorry Andy,

    I forgot the smiley face on post #8.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2015-02-20 16:35
    Not a problem. I did not take it wrong!!!
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